The Grenada gazette. (Grenada, Miss.) 1885-18??, 1887-12-10
shades of white and black. r

shades of white and black. The.
cases, however. + extremely rar'
> More common is partial color blint
ness, where tho sensation is dcfectiv
!, in relation to certain colors, but NJ
to all. This is of three kinds --rcf
blindness. green-blindncss and violet
: blindness. Cases Of the last variet
arc so seldom met with that the tori
+ color-blindncss. as commonly used
has reference 10 either red-blindnes
Or green-blindness.
Persons who are red-blind see al
red objects as a shade of gray, and tn
same is true Of the green blind as Il
green. A mixture of white and b!acl
in proper proportions will give to the
color blind the same sensation as the
different shades of red and green. I
is somewhat singular that while there
is no reason to doubt that color blind
ness is as old as man, it was not dis.
tinctly recognized and accurately de-
scribed until a little more than a hnn.
bred years ago.
The first case on record is that of a
shoemaker named Harris, who lived in
Mayport England. 1t is said that his
first suspicion of any popularity Of
vision on his part arose when he was
about four years old. Having by acct
dent found a child's stocking in tho
street he carried it to a house near by
to inquire for the owner. He noticed
that other people called it a red stock
ing, but could not understand why
they did so, as it seemed to him COM
plctcly described by calling it a
stocking, He observed, also, that
while the children with whom
he played could distinguish
the cherries on a tree by some pre-
tended difference of color, he could
only tell them from the leaves by their
difference in size and shape. He found,
too. that by mean of this difference in
color, or in some way which he could
not understand, they could see tho
cherries at n greater distance than lie
could, though in cases where their
sight was not assisted by the color.
he could sec objects at as great a dis
lance as any of them.
This case was described in 1777.
Seventeen years later the celebrated
English chemist, Dalton, described his
own case SO accurately and infinitely
that color blindness in general, and
especially the form Of it with which he
was afflicted namely, red blindness
has since been known as Daltonism.
He says hat he was never convinced
of any popularity of his vision until he
accidentally observed the color of the
flower geranium zonale by candlclight.
The flower was pink, but appeared to
him almost an exact sky-blue by day.
BY tho light of the candle, however, il
seemed to him not to have any blue in
it. being what he called red-a color
which forms a striking contrast to
blue. His friends. to whom he re-
ferred the matter, agreed that the
color was not materially different from
what it was by daylight. except his
brother, who was subject to the same
defect as himself. Two years after
ward he began to investigate the sub.
jact of colors. or color-blindncss. He
that he could distinguish but
or at most three, colors in tho
rainbow. These were yellow and
blue. Oh yellow, blue and purple. His
included the green, yellow.
and red of others. This was
the same Dr. Dalton who afterwards,
n Quaker and con%scientiously
opposed TO wearing bright colors. when
he had received the scarlet gown
Of a doctor Of laws for ~presenta.
lion at court, not only donncd it with.
objection. but also wore it for sew
'ral days upon the street. in happy
lnconsciousness of the effect which he
produced.
Color-blindness is largely hereditary,
affects males much moro frequent.
y than females. 1t exists from birth,
md there is no means known by which
t can be remedied. A temporary
condition of or-blindness Is occa.
met with, duo to disease or
injury. which passes away with the
condition which produced it. Tho
Existence of color-blindness in persons
occupying responsible positions in tho
abroad and marine services is u
'ource Of great danger TO the travel
ng public. and in most countries ex-
limitations r provided by law, for
he purpose of testing the color-p per.
of all applicants for these
positions. Golden Days.